The present invention relates to imaging apparatus for diagnosis use to noninvasively measure a quantitative distribution representative of biological function or metabolism in living body and to display the distribution.
Imaging systems for diagnosis use can be grouped into two types, morphological imaging systems and functional quantity imaging systems. With systems of the former type, we can observe the shape of internal organs or tissues. To supply more clinical informations, several kind systems of the later type are now developed. One example is magnetic resonance spectrum (MRS)-imaging system. It was known that some information on metabolic process in tissue can be obtain by measuring chemical shift of resonant frequency of P.sup.31. Accordingly, many efforts have been made for developing a clinical use MRS imaging system by adapting position mapping methods to the spectroscopic technique of an NMR spectrum analyzer. However, the system has not reached a practical level, because p.sup.31 resonant signals from a living body are very weak, and the measurement time becomes very long to obtain informations for spectroscopic analysis and position mapping.
Another example of imaging systems for obtaining a spatial distribution representative of a biological function in body is suggested in U.S. Pat. No. 4,281,645. According to that, in vivo monitoring of oxidative metabolism in an internal organ can be practiced through measurement of hemoglobin oxygenation with detection of near infrar red light transillumination.
In such a in vivo optical monitoring system, is a difficult to obtain a practical level of spacial resolution, because a light beam on a living body is heavily scattered at respective regions or organs in the body. The applicant of the present application proposed a multi-wavelength method for reducing the adverse effect of the light scattering in body, with U.S. patent application Ser. No. 07/479,171, now U.S. Pat. No. 5,148,022, filed Feb. 13, 1990.